Sources of energy

Classification of Sources of Energy, Fossil Fuels, Hydro and Wind Energy, Class 10, Science
Sources Of Energy

Good Sources of Energy

A good source of energy would be one :
1. Which would do a large amount of work per unit volume or mass.
2. Be easily accessible
3. Be easy to store and transport.
4. The source of energy has to be economical.
Classification of Sources of Energy

We can classify energy sources in different ways. One classification is based on the reserves (supply) of an energy source. Another is based on how long we have been using it.

Renewable and nonrenewable sources of energy
Renewable sources of energy are those which can be generated by us or which are constantly being generated by natural processes or whose supply is unlimited.

Nonrenewable sources of energy

are those which were produced in the past by natural processes, whose supply is limited and which we cannot generate ourselves .
Coal, natural gas and petroleum are nonrenewable sources of energy. Wood is a renewable source of energy although its supply is limited. But if we replant and use trees in a planned manner, we can be assured of a continuous supply of firewood. The sun, wind and flowing water are also renewable sources because of their unlimited availability. Unlike fuels like coal, nuclear fuels such as uranium are required in very small quantities to generate electricity. So, their reserves will last for a long, long time. They are therefore classified as renewable sources of energy.

Conventional and nonconventional sources of energy

Sources of energy that have been in use for centuries are called conventional sources of energy. Conventional sources include wood, coal, petroleum and flowing water. Conventional sources like coal and petroleum are nonrenewable, while sources like flowing water are renewable.
Sources of energy that we have started using in new ways or only in recent times are called nonconventional or alternate sources of energy. These include energy from the sun, the heat inside the earth (geothermal energy), tides, ocean waves, etc. Nuclear energy is also a nonconventional source. Note that nonconventional energy sources are renewable.
We have been using wind and biomass (like cow dung) for energy for ages. In that sense they are conventionual sources. However, they were not used conventionally to do tasks like electricity generation, which has now been made possible with improvement in technology. In that sense they can also be called nonconventional sources of energy.

FOSSIL FUELS

Fuels that were formed from the remains of dead plants and animals are called fossil fuels. These were produced by complex processes with the help of a series of natural events over millions of years. The most widely used fossil fuels are coal, petroleum and natural gas. Plants trap solar energy in the form of food, and animals get energy when they eat the plants. Since fossil fuels came from plants and animals, their ultimate source of energy is the sun.

We get a number of different fuels from coal and petroleum. For example, we get petrol, diesel, kerosene and LPG from petroleum, and coke and natural gas from coal. When burnt in air, fossil fuels give off heat, which is used for various purposes-from cooking to generating electricity. However, these fuels are nonrenewable, and their reserves are running out. Unfortunately, we cannot repeat the events that led to their formation.
Fossil fuels have played an important role in the technological advances made in the last three hundred years or so. Even today, most of the energy requirements of homes, industries and transport are met by fossil fuels. It is estimated that about 25% of our total energy consumption comes from coal. More than 90% of this coal is used for electricity generation  in thermal power plants.

Summary of Chapter

We cannot imagine the world without energy. The source of energy is important as well. There are various sources of energy available today to the mankind. On a broad sense, sources of energy can be categorized into non-renewable and renewable. Wood, coal, oil, natural gas are some of the non-renewable sources as they cannot be renewable. These are also called the conventional sources of energy. Nuclear fuels like uranium produce energy by fission process. Nuclear energy from sun is obtained by nuclear fusion process.

Conventional fuels and sources of energy cause a lot of pollution to mankind and hence there is a need for looking towards alternate sources of energy, which are most likely to be renewable. Solar energy, energy from wind, hydro energy, geothermal energy and energy from biomass are some of the alternate sources of energy. Wind energy can be harnessed by using wind mills that can be erected at suitable locations. Hydroelectric plants make use of hydro energy. In most of the rural areas biomass is utilized.


Characteristics of a Good Source of Energy

       •  Enables us to do a large amount of work per unit volume or mass.
       •  Is easily accessible.
       •  Is easy to store and transport.
       •  Is economical.

Burning coal or petroleum products causes acidic oxides to be released. Thermoelectric production of electricity involves turbines. In thermal power stations, fossil fuels are burned to produce steam, basically a form of heat energy. This steam runs a turbine, which rotates a generator to produce electricity.

In hydroelectric power stations, the kinetic energy of flowing water, which is actually the potential energy of water stored at a height, is converted into electricity. Plant and animal products, wood and cow-dung cakes, are used as fuels. The source of these fuels is called bio-mass.

Burning a given mass of charcoal generates more heat than burning an equal mass of wood. Cow-dung, crop residue, garbage and sewage are decomposed in the absence of oxygen to produce bio-gas.

Advantages of Bio-Gas:
       •  It is an excellent fuel with 75% methane.
       •  It burns without smoke.
       •  It has a high heating capacity.
       •  It is also used for lighting.

Wind is another freely available resource that is used for generating energy.

Alternative or Non-Nonventional Sources of Energy:
       •  Energy from the sun
       •  Energy from the sea
       •  Geothermal energy
       •  Nuclear energy

Black surfaces absorb more heat when compared to white under identical conditions.

Three Types Energy From the Sea:
       •  Tidal energy
       •  Wave energy
       •  Ocean thermal energy

Molten rock in the earth’s crust is pushed upward and trapped in certain regions called hot spots.

Nuclear energy is produced either by nuclear fission or nuclear fusion. Exploiting various sources of energy causes disturbances in the environment.